Carnivorous Plant Snaps Shut With 600 Gs

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A carnivorous plant that lives in bogs worldwide traps its prey
in less than a millisecond, more than 100 times faster than a
Venus flytrap can manage, a new study finds. The study is the
first to capture a high-speed recording of the plant's traps
snapping shut.

Utricularia, a genus of rootless
carnivorous plants, is better known by its common name,
bladderwort. There are more than 200 species worldwide, living in
fresh water and saturated soils. To survive without roots,
bladderworts trap and digest tiny organisms, including protozoa
and tiny crustaceans. They do so with small bladder-like traps
that line their stems.

The super-fast motion of bladderwort traps (which are a few
millimeters in size) is too quick to be seen with the naked eye.
So Philippe Marmottant of the Universite Grenoble in France and
his colleagues made high-speed recordings of bladderworts
snapping up crustaceans just a few millimeters long.

"We wanted to know how fast the trap was," Marmottant told
LiveScience. "There were several estimations, but no certitude,
because high-speed recordings were not available."

Expert trappers

The cameras recorded up to 10,000 frames per second, enough to
give the researchers enough resolution to slow the film down and
analyze how the bladderworts trap their prey. The traps closed
more quickly than the traps on
any other carnivorous plant, the researchers reported Feb. 15
in the journal Proceedings of the Royal Society B. On average,
the traps snapped shut in about half a millisecond. In
comparison, Marmottant said, the
Venus flytrap reacts to its prey in 100 milliseconds.

"Because the suction is so fast, with accelerations of up to 600
G [600 times the force of gravity], it is very difficult for any
living animal to escape such a trap," Marmottant said. (For
comparison, an astronaut feels about3.5 Gs during a space-shuttle
liftoff; and a mere 8 Gs will cause most people to black out.)

The tiny traps generate all this energy by spring-loading
themselves. First, glands in the traps pump out water. That means
the air inside of the traps is at a much lower pressure than the
surrounding water. The door of the trap bulges out, much like the
shape of a contact lens. When prey triggers tiny hairs on the
outside of the door, the
trap leaves begin to collapse inward, crumpling until – bam!
– the door opens and water and
prey rush in.

If nothing triggers the traps, Marmottant said, they start
spontaneously firing after a few hours. The spontaneous firing
may bring in phytoplankton or other microscopic plants that
wouldn't otherwise become a bladderwort meal.

"Such plants give extra food to the trap, that is thus
vegetarian, or omnivorous if you like," Marmottant said.

Mimicking the bladderwort

Humans might be able to learn a thing or two from bladderworts,
Marmottant said.

"The door movement is ultra-fast and forcible, but at the same
time highly precise, repeatable and fail-safe," he said. "It
might give inspiration for new deployable materials."

That could be a pipette-like device useful for deploying tiny
bits of fluid, Marmottant said. Such a device could be helpful in
the laboratory and in everyday devices such as ink jet printers,
which produce tiny ink droplets, he said.